In radio frequency (RF) applications, an RF receiver or a receiver portion of an RF transceiver may be required to tolerate the presence of large interfering signals lying within the passband that corresponds to a communication channel of interest. These interfering signals may have originated from users in adjacent channels and/or from transmission sources which may be relatively far removed in frequency from the channel of interest but whose large transmission power may still cause significant interference problems. These interfering signals may be referred to as blockers and their relative frequency and/or detected power to that of the desired signal may vary based on transmission scheme and/or operational conditions. The effect of interfering signals in the channel of interest may result in, for example, bit error rate (BER) degradation in digital RF systems and audible and/or visible signal-to-noise ratio (SNR) degradation in analog RF systems.
However, the ability to provide an interference-tolerant design may be difficult to accomplish as second-order distortion effects are increasingly becoming a limitation in circuitry utilized by the wireless receivers. For example, mixers and/or other circuitry which may be utilized to downconvert a channel of interest to a zero intermediate frequency (IF) or to a low IF may generate, as a result of second-order nonlinearities, spectral components from blocker signals which may be at or near DC. The effect of these spectral components may be to introduce a DC offset to the desired signals at the zero IF which may result in signal saturation or, as mentioned above, a noticeable degradation to the system's noise performance.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.